Traditional western construction practices for wood based home building are typically directed towards assembling a frame, formed from studs, upon which sheeting is installed in the form of plywood for outside surfaces and drywall for inside wall surfaces. The frame is first constructed by carpenters in a piecemeal fashion wherein the various members are cut and fastened into position. With the frame in place, sheeting is applied to form the wall surfaces. The frame provides the strength of the structure as the vertical stud members assume the load of the constructed walls. The top member of a wood frame, the top plate, is typically a horizontally disposed lumber section nailed to the vertical studs. Roof trusses rest on the top plate and are typically toe nailed to the top plate or an L-shaped clip is nailed into the top surface of the top plate and then nailed into a side surface of the roof truss. The attachment of the roof trusses to the top plate must have sufficient integrity to withstand uplift forces caused by wind load under the overhang of the roof. High uplift loads can pull the clip nails out of the top plate or dislodge the toe nailing. Also, the top plate is typically nailed to the studs, consequently uplift forces may also dislodge these fasteners by pulling the nails from the studs.
Wall systems comprising high in-plane end load bearing panels, such as disclosed by McDonald in U.S. Ser. No. 12/147,444, form hollow walls without studs or wood frame. These systems are often absent the wood frame top plate and therefore do not provide a nailing surface along the top of the wall for mounting clips or toe nailed roof trusses. These wall systems do not require a top plate as the panels forming the interior and exterior portions of the wall bear the load along the top end of the panel. The panels are secured in position by top and bottom sheet metal tracks to maintain the spacing between the panels and therefore no nailing surface is available along the top surface of a wall section. Similar challenges present themselves between stories when incorporating rim and floor joists.
There are a number of disadvantages exhibited when using toe nailing or L-shaped clips (L-clips) as indicated particularly when there is no top plate component suitable for receiving nails. In order to maximize the strength of a roof truss or floor joist mounting system, ideally the fasteners between the various elements should be in shear when load is applied. Toe nailing and L-clip arrangements all commonly include fasteners that are under tension under load thereby significantly reducing the strength of the connection that is critical under high wind uplift loads. In tension, nail type fasteners positioned vertically into the top surface of a top plate loose strength as the nails can be pulled out of the plate. Using an L-clip, fasteners fixing the clip to the truss are in shear under load, an ideal configuration; however, the fastening to the top plate is in tension. Toe nailing fasteners are primarily in tension under load.
Therefore, what is needed is an apparatus to secure roof trusses and floor joists to wall systems absent top plate nailing surfaces and to provide a means for connecting a roof truss or floor joist to a wall system wherein all fasteners are in shear.